Asymmetric reduction of (E)- and (Z)-methyl 2-chloro-2-alkenoates by use of fermenting bakers' yeast gave (R)- and (S)-2-chloroalkanoiceacids in 25 92% ee and 98% ee, respectively. The chemical yields were 10 40% for 2-chloropentenoate, 2-chloroheptenoate, but 65 70% for 2,4,4-trichloro- and 2,4,4,4-tetrachlorobutenoates. The substrates were found to be reduced after hydrolysis to the acids. The reactivity and stereoselectivity of the reduction were discussed. The reduction products, (R)- and (S)-2,4,4-trichlorobutanoic acids, were transformed to (S)- and (R)-2-amino-4,4-dichlorobutanoic acids, respectively.
In order to prepare a dichloro-substituted leucinopine analog, reaction of 2-amino-4,4-dichlorobutanoic acid with -ketoglutaric acid was investigated.